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将不同来源的玉米小斑病菌先在不同抗性玉米自交系后在感病的自交系幼苗上分别连续继代培养21代和5代的结果,所有菌株的寄生适合度属性如产孢量(SP)、病斑长度(LL)和侵染效率(IE)均有提高,潜育期(IP)的时间则缩短,这种变化在同一自交系上随继代代数的增长而愈甚。此外,不同属性的变化程度也不同,到21代时,SP、LL、IE 提高和 IP 时间缩短的组合率分别是72.2%、33.3%、47.2%和8.3%,这反映了控制属性的遗传基础存在差异。多数组合在感病自交系上培养5代后仍能保持前21代时所获得的变化特点,这说明属性的变化是不可逆的遗传变异,从而导致病原菌种内群体的组成发生变化,并进而影响抗病性的稳定和持久。系统聚类法的分析说明,单独用某一属性来标志寄主的抗病程度有片面性。属性间只有 SP 和 LL 的相关程度达到了极显著水平。
The results showed that the susceptible inbred lines of A. marcescens from different resistant maize inbred lines were continuously subcultured for generations 21 and 5, respectively. The parasitic fitness of all isolates, such as sporulation (SP), lesion length (LL) and infection efficiency (IE) all increased, while the incubation period (IP) was shortened, and the change was more in the same inbred line with the increase of subcultures very. In addition, the degree of change of different attributes is also different. By the 21st generation, the combination rates of SP, LL, IE improvement and IP time shortening are 72.2%, 33.3%, 47.2% and 8.3%, respectively, reflecting the genetic basis of control attributes has a difference. The majority of combinations maintained the phenotypic characteristics of the first 21 generations after five generations in susceptible inbred lines, indicating that the change in properties is an irreversible genetic variation that leads to changes in the composition of the population within the pathogen species, and thus Affect the stability and long-lasting disease resistance. The analysis of systematic clustering method shows that the resistance level of the host alone is marked by a certain attribute. Only the correlation between SP and LL reached an extremely significant level.